Generally, a wire bonding, a TAP bonding, a flip chip bonding, and the like have been disclosed as methods for bonding a semiconductor chip to a substrate. Meanwhile, the size of an electronic product is gradually minimized, and its performance is more enhanced. The number of bonding pads for input and output has increased, while the size of the chip used in the electronic product has gradually become smaller. Thus, the conventional wire bonding process for bonding the semiconductor chip on the substrate has arrived at its limit. Instead of the wire bonding method, a flip chip bonding method, which is not only superior in view of integrity or performance, but also has no wire connection process and has light weight and short length, has been widely used. The flip chip bonding method is a technology for forming a bump on a bonding pad of a chip and directly bonding the bonding pad of the chip on a lead pad of a substrate without connecting the bonding pad of the chip to the lead pad of the substrate using a metal wire.
FIG. 1 shows a view for explaining a conventional flip chip bonding.
Referring to FIG. 1, a flip chip bonding has a structure that, after forming a stud bump 13 on a bonding pad 12 of a chip 11 cut away from a wafer 10 and flipping the chip 11, the bonding pad 12 of the chip 111 is directly bonded to a lead pad 22 of a substrate 21. Here, the flip chip bonding is classified into a package type flip chip bonding for bonding a flip chip in a ceramic package and a on-board type flip chip bonding for directly bonding a flip chip on a main board.
FIG. 2 is a view showing an example of a package type flip chip bonding, and FIG. 3 is a view showing an example of an on-board type flip chip bonding. Referring to FIG. 2, a chip 11 is bonded to a ceramic package 22 by a flip chip bonding method. At this time, the package is mounted on a main board 25. The ceramic package 22 is sealed by a package cover 26. Referring to FIG. 3, after a chip 11 is directly bonded on a main board 25 by a flip chip bonding method, the part that is connected by bumps 53 is molded by resin and the like.
Meanwhile, in case of bonding a chip on a substrate as described above, a bonding strength or a production yield depends on the kind of a basic substance of the board 21. A conventional layer-built structure of a substrate, as shown in FIG. 4, consists of a basic substance, Cu, Ni, and Au. Specifically, after forming a pattern on the substrate, a surface treatment is performed to enhance an adhesive property. Here, the surface treatment is conventionally performed by plating with Ni or Au. At this time, a substance 21-1 of the substrate is FPCB, FR4, FR5, ceramic, or glass. That is, after coating with a Cu layer 21-2 on the basic substance 21-1, a pattern is formed. Then, a Ni layer 21-3 and an Au layer 21-4 are formed through an electroplating process to perform the surface treatment for enhancing an adhesion property.
However, according to a conventional flip chip bonding method, there have been problems in that, since a thermo-compression method that applies heat and compression when bonding a chip to a substrate is employed, a process rate is slow, the chip may be damaged due to high heat and compression, and, in case that a substrate to which a c hip is bonded or a pad of a wafer has a weak material, electrical bonding property deteriorates.
Further, according to a conventional layer-built structure of a substrate, there has been a problem in that, since a bonding strength or a production yield greatly depends on the kind of a basic substance of the substrate, inferior product may be generated.